1. Field of the Invention
The present invention is directed to a remotely controlled scrolling sign display device in which opposed rollers may scroll a web containing numbers, letters, or other indicia for display.
2. Prior Art
Remotely controlled scrolling sign display systems which utilize opposed rollers to roll a web are known.
The present invention is directed to a display system that may be used with highway signs that are visible by motorists at great distances. Certain elements of the display will be changed frequently, such as the price of fuel. It is advantageous for such systems to be remotely controlled for a number of reasons. Initially, they are not easily accessible because of the great height of the signs. Further, there is a risk of injury to personnel that work in the high, dangerous location. Also, the display system is not easily accessible in inclement weather.
The present system is often utilized with displays wherein each numeral or letter may range from 2 to 15 feet in height. It can be appreciated that the web containing the numerals 0 through 9, for example, will be of great length. The total radius (including the web) of one roller will, therefore, differ significantly from the other roller, particularly as the web nears each end.
As can be appreciated, the larger the display, the longer the web and, accordingly, the greater the difference in radius between the rollers. When the display is relatively small, the difference in radius of the rollers will not be that significant. The rollers could be designed to operate at the same speed without adverse impact. When the radius of one roller differs significantly from the other roller, the rollers will operate at different rotational speeds with respect to each other. If they did not, the web may sag between the rollers or, alternatively, be prone to tear.
An additional problem presented is the need for a brake mechanism so that one or both rollers do not overrun.
A patentability search has been conducted and the following references were uncovered.
______________________________________ U.S. Pat. No. PATENTEE ISSUE DATE ______________________________________ 4,741,118 Aiken et al. May 3, 1988 4,680,883 Stadjuhar et al. July 21, 1987 3,726,031 Singer April 10, 1973 4,773,176 Grehan September 27, 1988 4,110,925 Strand et al. September 5, 1978 4,707,938 Carssow November 24, 1987 4,173,087 Saylor et al. November 6, 1979 3,631,618 Habuka January 4, 1972 3,334,432 Bates et al. August 8, 1967 2,935,806 Young May 10, 1960 ______________________________________
Aiken (U.S. Pat. No. 4,741,118) discloses a scrolling mechanism having a single motor rotating in a single direction. A gear box connects a motor shaft to web rolls. The web rolls are coupled to a shaft by selectively engageable clutches, each of which includes a low voltage field coil. When energized, the clutch engages the shaft. With constant braking action provided by spring clips on the web rolls, the motor must continually work against the braking action.
Stadjuhar (U.S. Pat. No. 4,680,883) provides a pair of rollers moving a flexible message web. A tensioning system consists of a freely floating pulley that is connected to a biasing spring in order t accommodate the difference in radii between the rollers.
In Singer (U.S. Pat. No. 3,726,031), a pair of rollers is provided, each with a chain and sprocket connected to a reversible motor. Brackets or strips to which the rollers are mounted, are interconnected by a link which is driven by a reversible motor so that their horizontal alignment may be adjusted.
Grehan (U.S. Pat. No. 4,773,176) shows a scrolling mechanism including an infa-red ray detecting system. A driving mechanism includes a rotary shaft motor connected to sprockets which, in turn, are attached to rollers. A spiral spring within a sprocket, with a minimum tension at its middle point, compensates for the variation in diameter of the rollers.
Strand et al. (U.S. Pat. No. 4,110,925) depicts a scrolling mechanism which includes a drive roll and a take up roll connected to an endless sprocket chain driven by a reversible motor. The different rotational velocities due to different roll diameters are addressed through a helical torsion spring that is wound within the take-up roll. When the diameter of the drive roll is larger than the take-up roll, the spring causes the take-up roll to rotate faster than the drive roll.
Carssow (U.S. Pat. No. 4,707,938) provides two motors, one for each roller, which move a web or flexible panel. One motor runs while the other motor is off and provides a certain resistance. A coil compression spring around each roller abuts the frame and keeps the roller from rotating freely.
Saylor et al. (U.S. Pat. No. 4,173,087) provides a series of adjacent, parallel rollers. A helical spring is intermediate to each roller and its drive gear. Habuka (U.S. Pat. No. 3,631,618), Bates et al. (U.S. Pat. No. 3,334,432), and Young (U.S. Pat. No. 2,935,806) show other display devices.
Accordingly, it is a principal object of the present invention to provide a scrolling display device having opposed rollers with a web that may be scrolled upward to reveal elements wound around the lower roller, scrolled downward to reveal elements wound around the upper roller and tensioned to accommodate any sagging in the web.
It is an additional object and purpose of the present invention to provide a sign scrolling display device that would accommodate different speeds of the rollers as they operate while maintaining the web in a taut position.
It is a further object and purpose of the present invention to provide a braking mechanism for a scrolling sign display device that will retain the web in a taut position yet allow the drive motor to operate without undue strain.